THE British Medical Journal recently carried an annotation under the title "Conditions for Good Visibility,"1 based on investigations made by H. C. Weston at the National Physics Laboratory under the auspices of the Illumination Research Council and published by the Industrial Health Research Board of the Medical Research Council.

Weston's investigation was intended to test the value of a method suggested by Beutell2 for determining the level of illumination required for the efficient performance of any kind of work involving visual discrimination. The method is based on the proposition that the illumination required for any visual task, as compared with the simplest possible task, depends on certain conditions adversely affecting its performance, that these conditions can be defined and that if the relationship can be ascertained between each of the conditions and the illumination required to compensate for it then the illumination suitable for the performance of the